Among industrial apparatuses including programmable controllers, there are a type of the industrial apparatus that uses a sink current to control an input device and an output device and a type of the industrial apparatus that uses a source current to control an input device and an output device so as to address various applications of the apparatuses for users. Where a field effect transistor is used as an output transistor, an N-type output transistor is used for the sink-current type, and a P-type output transistor is used for the source-current type. Where a bipolar transistor is used as an output transistor, an npn-type output transistor is used for the sink-current type, and a pnp-type output transistor is used for the source-current type.
Hereinafter, in the present description, an N-type field effect transistor and an npn-type bipolar transistor, which are used in circuit configurations of the sink-current type, are collectively called an N-type output transistor. Likewise, a P-type field effect transistor and a pnp-type bipolar transistor, which are used in circuit configurations of the source-current type, are collectively called a P-type output transistor.
In order to address the various applications for users, manufacturers of electronic components need to line up both the sink-current type of products and the source-current type of products, and thus the number of kinds of printed-wiring boards of these products increases.
Patent Literature 1 and Patent Literature 2 below disclose a technique which uses the small number of components to achieve the sink-current type of output circuit and the source-current type of output circuit on the same board. This technique also switches from a state where the components are mounted on the board to a state where the components are not mounted on the board or vice versa, or switches the wire connections between the components, to reduce the number of kinds of the boards.
For the technique of Patent Literature 1, the programmable controller switches the connection route between an external power supply and the base electrode of an output transistor, such that the circuit configuration of an output circuit is switched between the sink-current type and the source-current type on the same board.
In Patent Literature 2, the connection route on the printed wiring is switched and the position in which to mount an insulating circuit package is switched, such that the circuit configuration of an output circuit is switched between the sink-current type of circuit configuration and the source-current type of circuit configuration on the same board.